According to the headrest moving device of the prior art, a headrest moving device having a tilting structure or a sliding structure has been suggested for discretionally adjusting the space between the headrest and the passenger's occipital region so that the headrest is being slanted at a certain angle by rotating the headrest around the fixed point thereof while the headrest is being fixed to the seat back.
The position of the headrest is adjusted by forming a plurality of teeth along the lengthwise direction when using a headrest having a sliding structure or a tilting structure as suggested in Korea Patent No. 0790535, Korea Utility Patent Publication No. 2000-0015501, Korea Patent No. 0403478, Korea Patent Publication No. 2007-0105210, and U.S. Patent Publication No. 2011-0221250. There has been limitation of using smaller teeth for fine adjustment of the position of the headrest since there is a problem that the teeth are easily damaged due to degradation of the durability of the teeth. Besides, there is a problem that the operation is disabled when some of the teeth are broken off. Moreover, there has been frequent instances when the headrest moving device is not being used even the headrest moving device is mounted in the vehicle not knowing how to disengage the locking of the headrest after the customer has moved the position of the headrest since the locking is disengaged only when the headrest is moved to the rearmost end.
In order to solve such a problem, a method for disengaging the locking at any position by providing a button which is connected to the slidingly moving shaft at the exterior of the headrest is disclosed in Korea Patent Publication No. 2010-0130000. However, when such a sliding shaft is provided, problems occur such as degradation of functionality and durability of the button, noise generation, and the like due to the friction between the button and the shaft.
In addition, a headrest provided with a solenoid valve for disengaging the locking is disclosed in Korea Patent No. 1071580. When the locking is disengaged by providing a solenoid valve, not only the manufacturing cost is increased but also the structure becomes complicated due to the wire connections and the like.